Etcoff’s current project, to map the parts of the brain excited by beauty, is a new effort to provide insight into how attraction works. Yu calls it the quest to find "the B-spot." He expects that the B-spot may differ more in westerners "because we’re more trained to like things" through the media than other cultures.

"We are very affected by beauty and ugliness," says Yu, adding that he can see why women worry about their bodies. He says that something other than natural selection is at work. "If you’re beautiful, you’re not genetically better."

Personally, Yu prefers what he calls "the Kate Moss type," the U9’s and the U7’s in the diagram, though he can't say if it’s an individual preference, or media influence that accounts for his taste. They are far from Etcoff’s hourglass ideal of a healthy breeder.

Either Way, Yu says, "My wife looks like that."